Steve, are you experiencing any vibration or swaying that would make you want to install one?? Several of the guys here on the site have taken the little shocks off of their 4-doors and had realized no ill effects afterwards. What makes you want one?
But if you were to install one, I'm sure it can be done. Now, I don't have a Sport so take this as you may... but if Ford put the same exact rear axle on the Sports as they put on the 4-doors, then your axle should have the same mounting point for the little shock on the top passenger side of the differential housing that mine does. Now I'm pretty sure that the Sport frames and the 4-door frames are different, so Ford may not have put the shock mount on the frame of the Sports like they did on the 4-doors. But that could be easily fixed if you made or bought a universal shock mount from a 4x4 shop and bolted or welded it onto your frame. Then you could mount you a little shock just like the 4 doors have.